Many internal combustion engines utilize turbo chargers to increase the performance of the engine. Turbo chargers increase the performance by increasing the mass flow rate of air into the air intake of the engine during operation. Turbo chargers typically operate as high speed radial compressors which increase the air pressure of the air prior to delivery of the air to the engine. The increase in air pressure also causes a temperature rise in the compressed air. After the air has been compressed, it is delivered to the intake of the engine.
To obtain maximum performance from the turbo charged air, the temperature of the air should be kept within an optimal range. If the turbo charged air is too hot, the density of the air will be reduced which increases fuel consumption. In addition, the higher air temperature will increase the piston temperatures of the engine which results in a reduction in the performance of the engine. Higher air temperature also increases nitrogen oxide exhaust emissions. Also, the lower density caused by the higher temperature will reduce the power level in the engine because of the lower amount of air in the piston. However, if the turbo charged compressed air is too cool, the engine produces increased visible and other emissions.
Also, the operating temperature of the engine should also be kept within a desired range. Systems for regulating engine temperature typically employ a system which circulates coolant through the engine to transfer heat from the engine to the coolant and then circulates the coolant through a radiator to cool the coolant before the coolant is circulated back into the engine. The coolant system may also employ fans which blow air across the radiators to improve the ability of the radiators to remove heat from the coolant.
However, during certain operating conditions, such as when the ambient air temperature is very low and the engine is operating at a low power output, if the coolant is circulated through the radiator the temperature of the coolant may be lowered to such a degree that when the coolant is circulated back through the engine, the engine is cooled to a temperature below it's optimal level.
To overcome this drawback in a loop system, it is known to utilize a system where when the sensed ambient temperature is too low and the engine is operating at low speeds, the coolant is circulated through an alternate path so that the coolant will not flow through the radiator. However, the radiator must be drained during this alternate condition to prevent the coolant in the radiator from freezing, which may damage the radiator. Systems which route the circulation of the coolant around the radiator and drain the radiators are referred to as wet/dry systems.
Frequently, the same coolant system circulates the coolant through an air cooler to reduce the temperature of the turbo charged air prior to the introduction of the air into the engine. If, however, the engine is operating at higher power outputs and the ambient temperature is high, the coolant will not be cooled, by passage through the radiator, to a temperature which adequately removes the heat from the turbo charged air. Thus, the air temperature of the turbo charged air will be higher than the optimal range.
On the other hand, when the engine is operating at a low ambient condition and/or at low power levels, the temperature of the coolant may so low that it causes the air coolers to cool the turbo charged air below it's optimal temperature range.
U.S. Pat. No. 5,201,285 to McTaggart discloses a Cooling System for a Turbo Charged Internal Combustion Engine which lowers the temperature of the coolant below the temperature of the coolant provided to the engine. In the disclosed system, the temperature of the coolant provided to the air cooler may be routed through an additional sub-cooler. In the disclosed preferred embodiment, the sub-cooler is disposed beneath the radiator and air is blown through the sub-cooler and radiator.
The disclosed system, however, has several drawbacks. One of the drawbacks is that when there is a low ambient temperature and the engine is operating at medium power levels, the air cooler coolant may be cooled to too low a temperature by the sub-cooler. When the coolant passes through the air cooler, the charged air may become too cool thus resulting in visible emissions.
An additional drawback is that when the ambient air temperature is low and the engine is operating at low temperatures, the coolant provided to the engine may be cooled to such a low degree that it causes the engine to run below the optimal range. Although the system does disclose a control valve which allows a portion of the coolant provided to the radiator to be routed around the radiator, there may be operating conditions where allowing even a limited flow through the radiator would cause the temperature of the coolant to become too low.
If, however, the disclosed system were to be modified so that in certain operating conditions, no flow of coolant flows through the radiator, then the stagnant coolant in the radiator may cause corrosion of the radiator and/or damage to the radiator if that coolant freezes.
Accordingly, it is an object of the present invention to provide a temperature regulating system to regulate the temperature of a turbo charged engine and the compressed air from the turbo charger being provided to the engine.
It is a further object of the present invention to provide a temperature regulating system for maintaining the operating temperature of the engine in a desired optimal range. A related object of the present invention is to provide a temperature regulating system for maintaining the temperature of the compressed air, provided by the turbo charger to the engine, in a desired optimal range.
It is another object of the present invention to provide a temperature regulating system in which a portion of the coolant from the engine which passes through the radiator is further cooled so that the air temperature of the compressed air from the turbo charger will be maintained in an optimal range.
A still further object of the present invention is to provide a heat regulating system in which heated coolant from the engine may be utilized to heat the compressed air from the turbo charger.
Yet another object of the present invention is to provide a heat regulating system in which under certain operating conditions the flow of coolant from the engine is circulated back to the engine without passing through the primary radiator. A related object is to provide such a system in which the radiator is drained when there is no flow of coolant through the radiator.